I have pre teens and this is just for 'fun' rather than to prep them for babysitting. They have younger siblings, so I feel that general info on taking care of children and the feel-good factor of having taken responsibility to do some independent learning online (like Mom does!) will be enjoyable for them.
So, recommendations please?
This is the best I've found so far, but everything has been minimal in terms of what is shows you as a taster of the course....
my daughter used http://www.babysittingclass.com/. it is $17.50US and she enjoyed it. it doesn't include cpr/first aid, though.